The horrible death of 15-year-old Billy Cox — shot on Wednesday in his own home on an estate in Clapham — could not have come at a more poignant moment: a day after Unicef published a provocative report claiming that British children have a worse deal than their counterparts anywhere else in the developed world. It is one thing to try to laugh off the reputation of the archetypal British teenage hoody for his junk-food diet and low cultural aspirations; quite another to overlook the fact that increasing numbers of young Britons are dying at the point of a gun.

It has taken a spate of three killings in South London in twelve days, and the conclusion of a murder trial, to bring home the fact that the victims and perpetrators of gun crime are getting younger and younger. Also on Wednesday an 18-year-old Angolan refugee, Roberto Malasi, was jailed for a minimum of 30 years for the cold-blooded shooting of a guest at a christening in Peckham and the fatal stabbing two weeks later of a woman motorist he felt had shown him “disrespect”. Remarkably, as has often been pointed out, we have now seen a doubling of gun crime in a decade since some of the tightest gun-control laws in the world were introduced.

Even the claimed success of Operation Trident, with gun killings in London falling from 18 in 2004-05 to 15 in 2005-06, obscures an uglier figure: that over the same period non-fatal shootings rose from 185 to 251. All of this appears to suggest that while Londoners continue to try to murder each other with guns they are becoming steadily worse shots. It may even be a function of the youth of the some of the shooters.

It isn’t easy to establish why gun crime should have become so prevalent. In spite of the recent youth killings having occurred less than a rifle shot from expensive South London residential suburbs, the underworld of the gun remains an obscure place. Nor, in spite of the small army ferried in for the grim task of taping off and examining murder scenes in recent days, are the police fully involved in resolving the problem.

This cannot be easily blamed on officers themselves: not when those communities oppressed by the gangsters are so reluctant to use the official forces of law and order except for the business of clearing away the bodies. According to one prisoner interviewed for a recent Home Office study, he began to carry a gun after being kidnapped, assaulted and dumped in woodland, shot at, and had seen a another man shot and robbed at gunpoint on several occasions. Yet not one of these offences did he, or anybody else, report to the police, for fear of reprisals.

That Home Office study, conducted by three academics from the University of Portsmouth and based on interviews with eighty prisoners, provides perhaps the best available insight into the rise of gun crime in London. Many of its findings, it is true, could easily be guessed at: for example, that most gun criminals are involved in the drug trade and that the black community is hugely overrepresented. Moreover, those involved with gun crime tend to have grown up fatherless and in the absence of good male role models have gravitated towards gangs whose names reflect the banal landscape of urban Britain, such as the “Burger Bar Crew”. Their members spend their lives pathetically in search of something they call “respect”, a quality that they seem to believe flows more readily if one wears thick gold chains and Nike Shox at £130 a pair.

Yet out of 170 pages of interviews do emerge some worthwhile insights, with repercussions for public policy. Above all there seems to be a connection between the Criminal Justice Act 2003 and the increasing tendency of youths to carry and use guns. The Act imposed a mandatory five-year sentence on any adult caught in possession of an illegal firearm: hence the need for criminals to appoint more innocent-looking youngsters to carry and look after their weapons for them.

Moreover, the mandatory nature of the sentence — which overlooks many young black men taking to carrying guns not in order to instigate criminal acts but to defend themselves after threats have been made against them — acts as a deterrent against suspects making early guilty pleas and cooperating with the police in investigating other crimes.

The evidence appears also to point against one argument favoured by middle-class drug users: that gun crime only happens because drugs laws keep prices artificially high, and that if recreational drugs were legalised, the market would collapse and the violence would subside. In fact, some of the criminals interviewed pointed to the falling price of drugs as a cause of the rise in gun crime: unable to afford their Nike trainers through peddling drugs alone, criminals have started robbing rival gangs.

The study also provides some evidence that the strict gun control laws introduced after Dunblane are at least doing something towards the growth in gun killings. While the price of a shotgun in the criminal underworld has fallen to £50 and the price of a handgun to £150, there is no great flood of illegal guns into the country. The weapons being bought and sold by criminals are mostly old or have been crudely converted from replica firearms. Frequently these fail to fire properly and in some cases have injured the user.

It would be reassuring to think that as the nation’s stock of illegal guns decreases further in quality they will explode in their users’ faces ever more frequently. But realistically we are only going to arrest the appalling spree of recent gun crime if we accept that the solution will involve more than simply scooping up and jailing for five years every black man caught in Peckham with a gun.

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